This invention relates to fire suppression systems for use with offshore oil platforms and in particular to a fluid conducting stab and stab receptacle system for use in conducting a supply of fire suppressing fluid from a service vessel to a platform.
Rising prices of hydrocarbon energy sources have made the offshore production of hydrocarbons economically attractive. Offshore production accounts for a large percentage of the worldwide oil production and that percentage is expected to increase in the future. The technical problems of providing oil drilling and production platforms in waters approaching a thousand feet of depth have been rapidly overcome. The cost of building the necessary structures usually can be justified only when a large number of wells are drilled from a single platform. The term "platform" is in fact somewhat misleading since the modern offshore oil platforms often more closely resemble a large multistory factory and hotel complex. While the platforms have become quite massive, space is still at a premium when it is considered that typically ten to fifty wells are drilled from each platform and large quantities of equipment must be provided near the wellheads during drilling and production. The wellhead locations are therefor usually surrounded by the equipment which, in turn, is housed in numerous compartments into which the multistory platforms are divided.
While it may appear that the simplest manner of fighting fires on a platform is to provide the fire fighting equipment on the platform itself, this arrangement is not practical for several reasons. In case of blowout, it is essential that all power on the platform be shut off immediately to avoid any sparks which might ignite escaping gas. It an explosion or fire has already occurred, damage to the platform is usually so extensive that it would be impossible to keep a power system in operation. Even if some power were available to operate a fire fighting system capable of pumping sufficient quantities of fire fighting fluids to the necessary locations, there would be no manpower available to operate the systems. When a blowout occurs, and in any case when a resulting fire occurs, the first concern is to evacuate the platform to avoid loss of life. As a result, the only means of fighting fires on offshore oil platforms has been from a vessel such as a fire boat or an auxiliary platform set up adjacent to the burning platform. In case of a blowout and fire at a wellhead, it has been found to be quite difficult to supply fire suppressing fluids, such as water or foam, to the location of the fire. That is, while typical fire boats have the capacity to pump large quantities of water and direct it toward a platform, the platform structure itself deflects essentially all of the water and prevents it from reaching a wellhead fire.
Another problem encountered in wellhead fires is loss of structural integrity of the platform itself. The most critical structural elements of the platform are those which connect the platform to the top of the supporting legs. The wells are drilled through the supporting legs so that the wellheads are necessarily positioned above the legs and above the critical structural points. In the case of a blowout and fire, hydrocarbon fluids may flow down through the structure and into or around the supporting legs while burning thereby heating the critical structural elements. If these points in the structure are weakened sufficiently by the heat, the entire platform may collapse with obvious disastrous results. It is therefore very important when fighting platform fires to pump large quantities of water to the structural elements at the point of interconnection with the supporting legs. But it is difficult to direct water from conventional fireboats to this part of the structure since the platform itself covers and surrounds this part of the structure. The fire fighting ships must typically direct the water upward to this lower portion of the platform structure from a fairly close and dangerous position and even then may only be able to cool one side of the support structure since the leg itself shields the opposite side from the spray of cooling water.
Thus, a system for directing large quantities of water to the platform structure at the junction of the structure and supporting legs would be highly desirable to avoid total loss of the structure in case of blowout and fire.